methyl 3,4-dihydro-2H-chromene-2-carboxylate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: At room temperature and while stirring, a solution of 36.4 g (0.19 mol) of 2-methoxycarbonylchroman in 400 ml of absolute tetrahydrofuran is added dropwise within a period of 1 hour to a suspension of 7.2 g (0.19 mol) of lithium aluminum hydride in 400 ml of absolute diethyl ether. After continuing to stir for a further 16 hours at room temperature, the reaction mixture is carefully decomposed with 7.2 ml of water, 7.2 ml of sodium hydroxide solution (15% strength) and 21.6 ml of water. The precipitate formed is filtered off with suction and the filtrate is concentrated by evaporation in vacuo. The oily residue is dissolved in diethyl ether. The ethereal solution is washed with water, dried over sodium sulphate and concentrated by evaporation in vacuo. 31 g (99.3%) of 2-hydroxymethylchroman are thus obtained in the form of a colourless oil. to stir for a further 16 hours at room temperature The precipitate formed is filtered off with suction the filtrate is concentrated by evaporation in vacuo The oily residue is dissolved in diethyl ether The ethereal solution is washed with water dried over sodium sulphate concentrated by evaporation in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: At room temperature and while stirring, a solution of 36.4 g (0.19 mol) of 2-methoxycarbonylchroman in 400 ml of absolute tetrahydrofuran is added dropwise within a period of 1 hour to a suspension of 7.2 g (0.19 mol) of lithium aluminum hydride in 400 ml of absolute diethyl ether. After continuing to stir for a further 16 hours at room temperature, the reaction mixture is carefully decomposed with 7.2 ml of water, 7.2 ml of sodium hydroxide solution (15% strength) and 21.6 ml of water. The precipitate formed is filtered off with suction and the filtrate is concentrated by evaporation in vacuo. The oily residue is dissolved in diethyl ether. The ethereal solution is washed with water, dried over sodium sulphate and concentrated by evaporation in vacuo. 31 g (99.3%) of 2-hydroxymethylchroman are thus obtained in the form of a colourless oil. to stir for a further 16 hours at room temperature The precipitate formed is filtered off with suction the filtrate is concentrated by evaporation in vacuo The oily residue is dissolved in diethyl ether The ethereal solution is washed with water dried over sodium sulphate concentrated by evaporation in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 14.2 ml of sulphuric acid (100% strength) are added to a solution of 70.34 g (0.39 mol) of 2-carboxychroman in 1400 ml of methanol and the whole is boiled under reflux for 4 hours. After cooling, the reaction mixture is concentrated by evaporation in vacuo and the residue is dissolved in diethyl ether and washed with water, cold saturated sodium hydrogen carbonate solution and again with water. The ethereal phase is dried over sodium sulphate and concentrated by evaporation in vacuo. 72.8 g (96%) of 2-methoxycarbonylchroman are obtained in the form of a pale yellow oil. under reflux for 4 hours After cooling the reaction mixture is concentrated by evaporation in vacuo the residue is dissolved in diethyl ether washed with water, cold saturated sodium hydrogen carbonate solution and again with water The ethereal phase is dried over sodium sulphate concentrated by evaporation in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Compound 3A was prepared by hydrogenation of the methyl 4-oxo-4H-chromene-2-carboxylate catalyzed by 10% Pd/C in 93% yield. MS: MS: 193 (M+1)+. Preparation of 6-Chlorosulfonyl-chroman-2-carboxylic acid methyl ester (Compound 3B)

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: At room temperature and while stirring, a solution of 36.4 g (0.19 mol) of 2-methoxycarbonylchroman in 400 ml of absolute tetrahydrofuran is added dropwise within a period of 1 hour to a suspension of 7.2 g (0.19 mol) of lithium aluminium hydride in 400 ml of absolute diethyl ether. After continuing to stir for a further 16 hours at room temperature, the reaction mixture is carefully decomposed with 7.2 ml of water, 7.2 ml of sodium hydroxide solution (15% strength) and 21.6 ml of water. The precipitate formed is filtered off with suction and the filtrate is concentrated by evaporation in vacuo. The oily residue is dissolved in diethyl ether. The ethereal solution is washed with water, dried over sodium sulphate and concentrated by evaporation in vacuo. 31 g (99.3%) of 2-hydroxymethylchroman are thus obtained in the form of a colourless oil. to stir for a further 16 hours at room temperature The precipitate formed is filtered off with suction the filtrate is concentrated by evaporation in vacuo The oily residue is dissolved in diethyl ether The ethereal solution is washed with water dried over sodium sulphate concentrated by evaporation in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 14.2 ml of sulphuric acid (100% strength) are added to a solution of 70.34 g (0.39 mol) of 2-carboxychroman in 1400 ml of methanol and the whole is boiled under reflux for 4 hours. After cooling, the reaction mixture is concentrated by evaporation in vacuo and the residue is dissolved in diethyl ether and washed with water, cold saturated sodium hydrogen carbonate solution and again with water. The ethereal phase is dried over sodium sulphate and concentrated by evaporation in vacuo. 72.8 g (96%) of 2-methoxycarbonylchroman are obtained in the form of a pale yellow oil. under reflux for 4 hours After cooling the reaction mixture is concentrated by evaporation in vacuo the residue is dissolved in diethyl ether washed with water, cold saturated sodium hydrogen carbonate solution and again with water The ethereal phase is dried over sodium sulphate concentrated by evaporation in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: At room temperature and while stirring, a solution of 36.4 g (0.19 mol) of 2-methoxycarbonylchroman in 400 ml of absolute tetrahydrofuran is added dropwise within a period of 1 hour to a suspension of 7.2 g (0.19 mol) of lithium aluminum hydride in 400 ml of absolute diethyl ether. After continuing to stir for a further 16 hours at room temperature, the reaction mixture is carefully decomposed with 7.2 ml of water, 7.2 ml of sodium hydroxide solution (15% strength) and 21.6 ml of water. The precipitate formed is filtered off with suction and the filtrate is concentrated by evaporation in vacuo. The oily residue is dissolved in diethyl ether. The ethereal solution is washed with water, dried over sodium sulphate and concentrated by evaporation in vacuo. 31 g (99.3%) of 2-hydroxymethylchroman are thus obtained in the form of a colourless oil. to stir for a further 16 hours at room temperature The precipitate formed is filtered off with suction the filtrate is concentrated by evaporation in vacuo The oily residue is dissolved in diethyl ether The ethereal solution is washed with water dried over sodium sulphate concentrated by evaporation in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 14.2 ml of sulphuric acid (100% strength) are added to a solution of 70.34 g (0.39 mol) of 2-carboxychroman in 1400 ml of methanol and the whole is boiled under reflux for 4 hours. After cooling, the reaction mixture is concentrated by evaporation in vacuo and the residue is dissolved in diethyl ether and washed with water, cold saturated sodium hydrogen carbonate solution and again with water. The ethereal phase is dried over sodium sulphate and concentrated by evaporation in vacuo. 72.8 g (96%) of 2-methoxycarbonylchroman are obtained in the form of a pale yellow oil. under reflux for 4 hours After cooling the reaction mixture is concentrated by evaporation in vacuo the residue is dissolved in diethyl ether washed with water, cold saturated sodium hydrogen carbonate solution and again with water The ethereal phase is dried over sodium sulphate concentrated by evaporation in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Compound 3A was prepared by hydrogenation of the methyl 4-oxo-4H-chromene-2-carboxylate catalyzed by 10% Pd/C in 93% yield. MS: MS: 193 (M+1)+. Preparation of 6-Chlorosulfonyl-chroman-2-carboxylic acid methyl ester (Compound 3B)